Behavioral Differences Between Colts and Fillies Examined

"The colts were less interested in exploring and in the unknown person, but they showed a high interest in getting back to the rest of their group (of familiar yearlings)," Wulf said.

Photo: Anne M. Eberhardt/The Horse

Many riders have a distinct preference when it comes to working with mares--they either love the girls or would rather avoid them. In some cases this choice is related to hormonal behavioral changes in mares during their heat cycles. But perhaps these behavioral differences are not just related to reproduction hormones. What if there was a fundamental difference in behavior between male and female horses?

This certainly appears to be the case, according to a group of German equitation scientists.

By studying the behavior ofprepubescent (not sexually mature) yearling colts and fillies, Manuela Wulf, BSc, researcher at the Graf Lehndorff Institute for Equine Science in Neustadt, and colleagues concluded that there is a definite trend towards fundamental gender differences in equine behavior--but not in the direction they had expected.

"We set out with the idea that colts were less anxious than fillies, as we know this to be the case with research on dogs and humans that show that boys are usually less anxious than girls," Wulf said during her presentation at the 2011 International Society for Equitation Science Conference, held Oct. 26-29 in Hooge Mierde, The Netherlands. "But what we found was that ... (our study) colts are definitely not less anxious than (our study) fillies."

For her study, Wulf employed six male and nine female Warmblood yearlings raised in identical conditions. Once daily for five days the young horses were brought into an arena alone with a previously unknown human. The human would stand motionless for a short period of time (five minutes the first day and one minute the other days), then would approach the horse to put a halter on it, and try to manipulate the horse by brushing its hair coat and picking up its feet. The researchers observed the horses' behavior and monitored their heart rates (an indicator of stress or anxiety) throughout the tests.

"The fillies were a lot more eager to explore the surroundings and also to show interest in the unknown person during the stationary human test," Wulf said. "The colts were less interested in exploring and in the unknown person, but they showed a high interest in getting back to the rest of their group (of familiar yearlings).

"Also, the time needed to approach the colts for haltering was a lot longer," she added. "But they adapted very quickly (over the days)." The colts were also more reluctant to have their legs picked up.

Interestingly, gender did not affect heart rate or the horses' ability to get accustomed to the human and the manipulation during the testing period, according to Wulf. "There was no difference in stress reactions when we look at the heart rate itself," she said. "And we did definitely see habituation effects over time, irrespective of gender."

Overall, the researchers found that while each horse has its own individual behavior patterns, the colts in the study were more anxious and distractible than the fillies.

Although this initial study shows a clearly detectable behavior difference between genders before puberty, Wulf acknowledges that more research is necessary with prepubescent horses, as her study was limited to only 15 yearlings.

About the Author

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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